Complimentary 
NEW SERIES VOL. II 
NO. 10 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN. MASS. JULY I. 1916 
Tree Lilacs. This name is often given to three large-growing Lilacs 
of northeastern Asia which are now in flower and are conspicuous 
objects in the Arboretum. These plants all have white flowers in 
large clusters, and differ from other Lilacs in the shape of their 
flowers. In all other Lilacs the tube of the corolla is much longer 
than the calyx and longer than the stamens which are enclosed by it, 
while in the Tree Lilacs the tube of the corolla is not much longer 
than the calyx and shorter than the stamens which are therefore seen 
when the flowers open. On account of this difference in their flowers 
the Tree Lilacs have been thought by some botanists to belong to a 
different genus to which the name Ligustrina was given, and this is 
now the name of the section of the genus Syringa in which they are 
placed. The three species are much alike and only differ in the shape 
of the leaves, in the size of the flower-clusters and in the time of 
flowering. They lose their leaves early in the autumn without any 
change of color, and in this early shedding of their leaves is found 
their only drawback as garden plants for they are all hardy, grow 
rapidly, are good in habit and bloom freely, although the flowers of 
one of the species, Syringa japonica, are usually produced more abund- 
antly in alternate years. The first of these plants to bloom, S. amur- 
ensis, is a native of eastern Siberia and northern China, and is a 
small, bushy, rather flat-topped tree which in cultivation rarely exceeds 
twenty feet in height. The leaves are thick, dark green, long-pointed, 
from three to four inches long and from two and a half to three 
inches wide, and the spreading and slightly drooping flower-clusters are 
usually from twelve to fourteen inches long and broad. This plant 
was first raised in this country before 1870 in the Harvard Botanic 
Garden from seeds received from the Botanic Garden at St. Peters- 
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